Maybe Jon Udell still hasn't seenXopus. I can't blame him. We (Q42) don't have a marketing department, and our Xopus site looks
like we don't want you to use it. But Xopus does seem to bewhat Jon Udell is looking for.

I guess I wasn't
paying
attention. The Xopus
demo is, indeed, an eye-opener.
Runs in the browser, without plug-in support, toggling between
WSYIWYG and XML modes, enforces schema, has multilingual support
both in the UI and the document. Includes a competent table editor.
The developers of this open-source project have even built a
prototype of
the MSIE
ContentEditable feature for Mozilla, in advance of official
support in Mozilla for that feature. Impressive!